JPS58120013A - Burner - Google Patents

Abstract

PURPOSE:To miniaturize a combustion chamber and a fan in a burner, by dividing a burner port into two parts, and by feeding air to flames formed on the burner ports, from both sides of the secondary and the tertiary air ports. CONSTITUTION:The secondary air is injected into flames formed on burner ports 7, from both sides of the secondary air ports 8, while the tertiary air, is injected into the flames from the tertiary air ports 12, passing through the center passage. Accordingly, the air can be sufficiently mixed with unburnt component in the center part of flames, even if the injection velocity to feed the air is small, and the length of flames can be shortened. With such an arrangement, the sizes of a fan and a combustion chamber can be miniaturized at the same time, because low blast pressure is enough for the burner, when the injection velocity of fed air is decreased. In addition, the injection velocity at burner ports on the downstream side becomes extremely low by providing a step 20 to the burner port, therefore, flow off of the flames can be prevented, and stabilized combustion can be secured on a burner.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a fan to forcibly supply air to the flame of household combustion appliances such as water heaters and space heaters to shorten the flame. The present invention relates to a combustion device that can reduce the size of the fan and the entire combustion device, and maintain stable combustion even when the combustion amount is varied widely for ease of use.

A combustion device shown in FIG. 8 is a conventional combustion device in which a flame port, a combustion chamber, and the like are integrally molded using a bilaterally symmetrical molded body made of a good thermally conductive material to achieve miniaturization.

This was applied to a hot-air heater using an all-fire combustion method in which the missing air volume was set to be higher than the theoretical air volume. Combustion chamber 1
02. Also, the internal fins 103 and external fins 104 are integrally molded. A pair of side plates 107 each having a mixture supply port 105 and an exhaust port 106 are provided on both sides of the molded body 1o○, and a mixture passage 108 and an exhaust passage 109 are provided on the top and bottom surfaces of the mixture supply port 106, respectively. and an exhaust port 106, respectively. In such a configuration, the mixture supply port 1
The mixture supplied from 05 is uniformly mixed while passing through the mixture passage 108, and uniformly jetted from the flame port 101 to form a flame on the flame port. Combustion gas generated in the combustion chamber 102 exchanges heat with the internal fins 103, and radiates heat with the external fins 104 to generate warm air. Internal fin 103
The combustion gas that has undergone heat exchange is discharged to the outside from the exhaust port 106 through the exhaust passage 109'i.

In the above-mentioned combustion devices, secondary combustion is performed, so the combustion speed is high and the flame is short, making it possible to configure the combustion chamber to be small. Also, secondary air is not required, making the device simpler and more compact. is planned. However, on the other hand, oscillatory combustion accompanied by abnormal noise is likely to occur, and in order to avoid this, it is necessary to investigate the shape and configuration of the mixing region and combustion equipment where oscillatory combustion does not occur, control the flow rate of fuel and air with high precision, and modify the equipment. assembly is required. In addition, in general, LP gas, natural gas, various city gases, and combustion engines that vaporize oil have different calorific values, combustion speeds, and other physical properties, so the configuration and shape of the mixing area and equipment that generate oscillatory combustion may vary. It is very difficult to make it universal, as the settings of each part must be changed depending on the type of fuel. Furthermore, especially when applied to water heaters, it is possible to respond to seasonal changes in water temperature and air temperature in order to improve usability, and the flow rate of hot water used can be significantly changed, and the amount of combustion can be changed accordingly. It is required to maintain stable combustion even at low temperatures. In other words, the ratio between the maximum combustion amount and the minimum combustion amount that can maintain a good combustion state, so-called TDR (Turn
Down Ratio )i is required to be increased. However, in the all-fire combustion method, the combustion speed is fast, so the flame burns in close contact with the flame mouth, increasing the flame temperature. Therefore, as the amount of combustion is reduced, the injection velocity of the air-fuel mixture decreases, the flame adheres more closely to the flame nozzle, and the flame nozzle temperature increases more and more. On the other hand, the air-fuel mixture passing through the flame nozzle is heated more and more, and the combustion speed increases in proportion to the rise in air-fuel mixture temperature, and eventually exceeds the air-fuel mixture injection speed, causing flashback. In addition, compared to the so-called Bunsen combustion method, which is the most common type of household combustion device, in which the amount of primary air is set below the theoretical amount of air, blow-off is more likely to occur when the amount of combustion is increased. This is because as the theoretical air amount increases, the region where blow-off occurs expands to the region where the air-fuel mixture jetting velocity is small. In other words, in the all-fire combustion system, the stable combustion range whose upper and lower limits are constrained by blow-off and Franschbach, respectively, is narrower than in the Bunsen combustion system.
It is extremely difficult to make it larger.

Another conventional example is shown in FIG.

This uses Bunsen combustion to forcibly supply secondary air into the flame to shorten the flame, making the combustion chamber smaller and reducing the size of the combustion device. Its structure is such that a mixture passage 111. A secondary air chamber 113° having a secondary air port 112 at the tip of the constriction portion and a burner element 116 having flame port portions 114 integrally molded on both sides of the secondary air chamber 113 are inserted, and the burner element 116 and the molded body are inserted. This is a combustion device in which two spaces partitioned by 110 constitute an air-fuel mixture chamber 116 and a combustion chamber 117, respectively.

In such a configuration, the mixture flows out into the mixture chamber 116 through the mixture passage 111, passes through the gap between the nozzle element 116 and the molded body 110, and reaches the flame port 114. The air-fuel mixture that has passed forms a flame as shown in the figure on the flame port 114.On the other hand, the secondary air passes through the constriction part from the secondary air chamber 113 and enters the secondary air port 112 provided at the tip. The gas is ejected from the flame and is forcefully supplied to the flame.

In the above-mentioned combustion equipment, since Bunsen combustion is performed, the stable combustion range whose upper and lower limits are restricted by blow-off and flash bank is wider than in the case of full-primary combustion, and the TDR can also be expanded. Also, the vibration combustion area is narrow. However, in Bunsen combustion, the flame stretches for a long time, so in order to make the combustion chamber smaller, secondary air is forcibly supplied to the flame and mixed with the secondary air as shown in Figure 9, which promotes the combustion reaction and shortens the flame. must be realized. Therefore, in this case, the most important point is how to supply the secondary air. In particular, the ejection speed of secondary air is an important parameter.
The lower limit is the minimum speed at which secondary air can be supplied to the flame, and the upper limit is the ejection speed when the flame blows off, or the incomplete combustion where the flame is supercooled before that and the combustion reaction freezes, producing a large amount of CO etc. This is the speed at which . In addition, the blowing pressure of the fan must be increased in proportion to the square of the secondary air blowing speed, so in order to downsize the combustion equipment including the fan, the secondary air blowing speed should be reduced as much as possible. We must make it smaller and achieve a shorter flame.

In the combustion device shown in FIG. 8, since the flame directly contacts the molded body 110, it is easily subjected to flame cooling, and especially when the combustion amount is made small, the balance between the amount of heat generated by the flame and the amount of heat taken away to the molded body 110 is lost. If the fuel has a low combustion speed, the flame will be supercooled and incomplete combustion will occur. Further, in the case of fuel having a high burning speed, the flame comes into close contact with the flame port 114 and heats it. On the other hand, in the vicinity of the molded body 110 of the flame mouth part 114, the flame mouth part 1
14 has an unreasonably small heat capacity. Further, since the contact area with the molded body 110 is small and the amount of heat transferred to the low temperature molded body 11o is small, the temperature of the flame opening in this area tends to rise, and therefore, flash banks are likely to occur. Therefore, TDR cannot be made that large. When the amount of burnt combustion is large, the flow rate of the mixture flowing out from the flame port 114 is high. Therefore, unless the flow rate of the secondary air supplied from the secondary air port 112 is also increased, the compact 1
Air cannot be supplied to flames close to 10. Furthermore, where the burner element 115 is supported by the molded body 110, the contact area is small as described above, so the amount of heat that the flame mouth part 114 receives from the flame is not transmitted to the molded body, and most of the heat is transferred to the secondary air chamber 113.
is cooled by secondary air passing through. Therefore, the secondary air is heated and expanded, increasing the blowing resistance. In other words, the amount of combustion is K
In the case of high pressure, the secondary air ejection speed must be increased and the blowing resistance increases, which requires a high blowing pressure from the fan, which increases the size of the fan and makes it difficult to downsize the combustion chamber. Are you a fan? As a result, the overall size of the two-combustion station including this cannot be reduced.

As explained above, in conventional combustion equipment, the following improvements have been made: - Miniaturization of the combustion equipment, miniaturization of the 7J equipment body including the fan, universality for fuel types, expansion of TDR, and expansion of the combustion range. It wasn't satisfying.

The present invention eliminates these conventional drawbacks, and simultaneously reduces the size of the combustion chamber and the fan, thereby reducing the overall size of the combustion device. The purpose is to realize a combustion device that has universal properties for stable combustion and maintains stable combustion even when the combustion amount changes significantly to improve usability. In the present invention, a flame port is provided on both sides of a tertiary air passage body whose tip portion having a tertiary air port projects into the center of the combustion chamber, and a secondary air chamber is provided in the molded body constituting the flame port. In addition, a secondary air port communicating with the secondary air port is provided near the burner port, and a portion of the burner port supports the tertiary air passage body.

With this configuration, the flame caused by the premixture supplied with primary air is split into two parts, which are supplied with secondary air from the secondary air ports on both sides for partial combustion, and then by the tertiary air supplied from the tertiary air supply port in the center. It will burn completely. Here, since each combustion air is supplied from the vicinity of the flame to be formed or from the center thereof, even if the jetting speed is small, it is possible to sufficiently supply the unburned components at the center of the flame. That is, since a short flame can be achieved with a low injection pressure, the combustion chamber and the fan can be made smaller at the same time. In addition, the flame opening is formed of the same molded body made of secondary air and a good heat conductor, and since it is in contact with the tertiary air passage, it is air-cooled from both sides by the secondary air and tertiary air, so the fuel burns quickly. However, the device can be made uniform without causing the entire flame to become red hot and causing a backlash. Furthermore, since the tip opening of the tertiary air passage body is semicircular, when the amount of combustion is large, the amount of air supplied is large and the ejection distribution spreads in the direction of the hooks on both sides, allowing it to mix with unburned components in a wide area. and promotes combustion reactions. On the other hand, when the combustion amount is reduced, the amount of supplied air is reduced and the air does not spread in the direction of the hooks on both sides. Therefore, the flames on both sides, where the flame temperature is low, are not supercooled and the combustion reaction is not frozen. Therefore, it is possible to set a large TDR. By changing the cross-sectional area of the flame side and mixture side of the flame hole, even if the air volume changes, the space between the part of the flame side where the mixture flow rate is slow and the tertiary air outlet jetting area can be reduced. It plays the role of flame retention, making it difficult to lift, and also prevents backlash by increasing the amount of tertiary air in response to the temperature rise during flame holding, and - maintains a stable combustion range even against fluctuations in air volume. It is something that can be expanded.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

In FIGS. 1 to 6, a fan 1 is connected to one side of a molded body 2 made of a heat conductive material, and a dividing plate 3 is provided in the vicinity thereof. The molded body 2 is provided with a secondary air chamber 4 inside, and a part of the member forms a thick convex part 6, and this convex part 5 has a large number of slit-shaped flame ports 6 arranged in a row. The flame opening 7 is formed by the flame opening 7. A plurality of secondary air ports 8 communicating with the secondary air chamber 4 are provided near the flame port. The molded bodies 2 are bilaterally symmetrical, and a pair of molded bodies 2 are joined to form part of an air-fuel mixture chamber 9 and a part of a combustion chamber 10.

A hollow tertiary air passage body 13 having a large number of slit-shaped tertiary air ports 12 at the tip of the throttle portion 11 is inserted into the mixture chamber 9, and a gap 14 is formed between the molded body 2 and the flame port 7. A pressure equalization chamber 16 is formed between them.

Here, the throttle v part 11 is supported from both sides by a pair of flame port parts 7, and the tertiary air port 12 faces into the combustion chamber 10. A stepped portion 20 (Fig. 3) is provided on the outer wall constituting the throttle portion 11, and the opening area on the mixture side 16 and combustion chamber side 10 of the flame lower is changed, and the cross-sectional area of the flame opening constituting the flame is changed to that of the mixture. It is larger than the cross-sectional area of the passage.

A water cooling pipe 17 is integrally formed on the combustion chamber wall 16, and a heat exchanger 18 and an exhaust port 1 are provided on the downstream side of the combustion chamber 10.
9 is provided.

To explain the operation of the above configuration, the combustion air supplied by the fan 1 is divided into primary air supplied into the mixture chamber 9 by the dividing plate 3, and secondary air supplied into the pair of secondary air chambers 4. air and tertiary air supplied into the tertiary air passage body 13.

On the other hand, the fuel passes through the entire fuel vibrator 23, its flow rate is adjusted by the control valve 21, and is then injected and supplied into the air-fuel mixture chamber 9 through the nozzle 22 at the tip. The fuel and primary air supplied into the mixture chamber 9 are uniformly mixed as they pass through this chamber, and pass through narrow gaps 14 on both sides of the tertiary air passage body 13. Due to the throttling effect of the gap 14, the air-fuel mixture is uniformly supplied to the pressure equalizing chamber 16, and uniformly injected into the combustion chamber 1o from the flame port 7 to form a flame on the flame port 6.

- The secondary air supplied to the pair of secondary air chambers 4 is forcibly ejected from both sides through the secondary air ports 8 and is partially combusted. Furthermore, the tertiary air supplied to the tertiary air passage body 13 passes through the constriction part 11, and is injected and supplied to the flame from a large number of slit-shaped tertiary air ports 12 provided at the tip with a fan-shaped ejection distribution. Therefore, the flames formed on the pair of flame corners 7 sandwiching the throttle part 11 are mixed in a wide area, the combustion reaction is promoted, and a short flame is realized.

Since the flame has become shorter, the combustion gas in the combustion chamber 10 will locally form a high temperature area, but a part of the generated heat will be cooled by heat exchange through the water cooling pipe 17 integrally formed on the combustion chamber wall 16. After exchanging heat with a heat exchanger 18 provided on the downstream side, it is discharged to the outside through an exhaust port 19.

Here, the flame formed on the flame throat part 7 is supplied with secondary air from both sides from the secondary air port 8, and tertiary air from the central part of the tertiary air port 12. Therefore, even if the ejection speed of the supplied air is small, sufficient air is supplied by the unburned components in the center of the flame, and a short flame can be realized. Therefore, as described above, if the blowing speed of the supplied air is reduced, the blowing pressure can also be reduced, and the size of the fan and the combustion chamber can be reduced at the same time. FIG. 4 shows this, and the blowing pressure of the fan for the same combustion chamber load is significantly reduced.

Furthermore, since the flame is not in direct contact with a cooling object such as the combustion chamber wall, even if the combustion rate is low, even if the combustion amount is reduced, stable combustion will occur without overcooling. Even when the amount of combustion is reduced using fuel with a high combustion speed, the flame adheres to the flame nozzle 6 and heats the flame nozzle 7, but the flame nozzle 7 is a molded body that is integrated with a good thermal conductor. Flashback does not occur because the secondary air flowing through the secondary air chamber 4 through the burner 2 and the tertiary air flowing through the constriction part 11 in contact with the flame outlet 7 effectively and quickly cools from both sides. Therefore, even when various fuels with different characteristics are used, stable combustion can be achieved and universality can be achieved.

Furthermore, since the tertiary air port provided in the center of the combustion chamber has a semicircular cross section, when the combustion amount is large as shown in Figure 6 B, the amount of air supplied is also large, and The ejection distribution is wide, and mixing with unburned components and combustion reaction are promoted over a wide area, so a short flame can be easily achieved. On the other hand, when the combustion amount is reduced, as shown in FIG. 5, the amount of supplied air decreases, so that the flame does not spread toward the flame openings on both sides. Therefore, there is no need to overcool the flame and freeze the reaction by supplying more air to the combustion reaction zone where the secondary air is sufficient and the flame temperature is low. FIG. 6 shows a concrete example of all the above contents. As can be seen in FIG. 6, the TDR can be increased, and the permissible fan air volume that can maintain stable combustion relative to the combustion amount is also increased, making it easy to achieve the combustion amount (2).

Furthermore, in the case of a mixture with an increased amount of primary air, the flame tends to be blown away, but as shown in FIG. The ejection velocity distribution of the air-fuel mixture ejected from the pressure chamber 15 is as shown by the dashed-dotted line a, and the ejection velocity at the downstream flame hole portion of the stepped portion 20 is extremely low.

Therefore, when the mixture becomes a mixture with a large amount of air, the flame becomes short and the flame is easily blown away, but in the region where the mixture jet flow velocity is low, it plays a flame-holding role, as shown by the dotted line in Figure 7. As shown in FIG. 6, a combustion flame is formed that is surrounded by the downstream flame hole of the stepped portion 20 and the end of the tertiary air port 12, thereby preventing blow-off and making it easier for the tertiary air to absorb stable heat as shown in FIG. , to prevent backlash.

As is clear from the above description, the combustion apparatus of the present invention provides the following effects.

(1) By dividing the flame nozzle into two parts and supplying air to the flame from both sides through the secondary air port and tertiary air port, a small jet of supplied air is emitted from the flame formed on each flame nozzle. By achieving a shorter flame at higher speeds, it is possible to achieve both a smaller combustion chamber and a smaller fan at the same time, making it possible to reduce the overall combustion load including the fan.

G2) The flame outlet is cooled by secondary air flowing through an integrally molded secondary air chamber on one side, and tertiary air flowing through a tertiary air passageway in contact with the flame outlet on the other side. Even when using fuel with a high burning rate, it does not heat up the flame nozzle and cause a flash bank. In addition, since the flame is formed in the center of the combustion chamber and does not come into direct contact with cooling parts such as the combustion chamber, even fuel with a low combustion speed will not be cooled by the flame and freeze the combustion reaction. Combustion equipment can be made universal for various fuels.

(3) Since the tertiary air port has a semicircular cross section, when the air volume is large and the combustion volume is large, it spreads toward the flame openings on both sides and effectively supplies air to the flame, and when the air volume is small and the combustion volume is small. Since the flame temperature on both sides is low, the flame does not spread in the direction of the flame, so there is no overcooling of the flame. Since the tertiary air supply direction changes in accordance with the combustion amount in this way, TDRi can be expanded. Furthermore, since the permissible fan air volume that can maintain stable combustion is increased, the amount of combustion (goods) becomes easier.

(4) By providing the stepped portion 20 in the tertiary air passage body 15 and changing the passage cross-sectional area before and after the flame port 6, a flame holding area is created against fluctuations in primary, secondary and secondary air, resulting in stable combustion. It has a flame hole configuration that expands the area.

(6) The tertiary air passage body 16 is provided with a constriction portion 11 to facilitate increasing the flow velocity of the tertiary air, making it easier to absorb heat from the flame, preventing backlash, and widening the combustion range.

As described above, the combustion device has a wide combustion range and is highly effective against high load/short flame and expansion of the stable combustion range during TDR, as well as fluctuations in primary and secondary air.

[Brief explanation of drawings]

Fig. 1 is an overall cross-sectional view of a combustion device showing an embodiment of the present invention, Fig. 2 is a partial cross-sectional view of Fig. 1, Fig. 3 is a perspective view of a partial cross-section of Fig. 1, and Fig. 4 is a combustion Figure 5a is an explanatory diagram showing the flame formed in the combustion device of Figure 1 and the ejection distribution of the supplied air, with a large amount of combustion. FIG. 6 is a cross-sectional view of an example in which stable combustion is maintained with respect to the combustion amount. 1...Fan, 2...Molded body, 4...
...Secondary air chamber, 6...Convex portion, 6...
...flame port, 7...flame port, 8...secondary air port, 1o...combustion chamber, 12...group/tertiary air port, 13. ...Tertiary air passage body, 2o...
...Danbe 0 Name of agent Patent attorney Toshio Nakao and 1 other person 1st
Zuka 2nd diagram 3rd cause 4th figure: 蜆王致贴MEπ7 HC mei. 1A8rI! J W/A9 figure//ρ 78-

Claims (1)

[Claims] A means is provided to shorten the flame by forcibly supplying air to the flame premixed with primary air using a fan, and the tip, which has a semicircular cross section with numerous tertiary air ports, is placed in the center of the combustion chamber. A convex portion is provided on a part of the molded body of a good thermal conductor that forms a tertiary air passage body protruding from the side and a secondary air chamber, and a flame mouth portion having a large number of flame nozzles is formed in the convex portion. In addition, a large number of secondary air ports communicating with the secondary air chamber are provided in the vicinity of the flame port, and the tertiary air passage body is supported from both sides by the flame port, and the air passage body is provided with a stepped portion. The tertiary air flow velocity was increased by setting a constriction part in the tertiary air passage body and guiding the flame opening at the flame opening, making the flame opening cross-sectional area on the flame side of the flame opening larger than the later passage cross-sectional area of the air-fuel mixture. Combustion device.